Folding knives are invaluable tools that are used in many aspects of everyday life, and there are many, many types and styles of folding knives. A “manual” folding knife is a very traditional type of tool in which the knife blade is manually movable by the user between a closed or stowed position in which the sharp edge of the blade is held safely within the handle, and an open position in which the blade is extended in an operable position. Most modern versions of manually operated folding knives include locking mechanisms that lock the blade in the open position—the safety benefits of such locks are obvious. There are innumerable variations on these basic themes.
Automatic folding knifes are nearly as ubiquitous as manual folders. These knives include some type of a mechanism—almost always a spring-driven mechanism—that drives the blade from the closed position toward the open position when the user activates the automatic mechanism, typically by pushing a button or analogous activating mechanism. Generally speaking, in a knife that has an automatic opening mechanism the blade is held in the closed position by a latched trigger mechanism. When the blade is in the closed position the blade is under a constant “pre-load” pressure from a spring mechanism. When the trigger is released, the blade is automatically driven by the spring mechanism into the open position. As with most modern versions of manual knives, most automatic folding knives include locks that lock the blade in the open position. When the user “unlocks” the blade to move it from the open position to the closed position, the rotation of the blade as it is moved reloads the spring mechanism so that the blade is ready to fire again when desired.
Most folding knives, whether manual or automatic, incorporate some kind of a mechanism that holds the blade or working implement in the closed position in which the sharp edge of the blade is held safely within the handle. There are many known mechanisms for retaining blades in the closed position, and there are obvious reasons why such mechanisms are used. Among other reasons, blade-retaining mechanisms prevent unintended opening of the knife and thus promote safety. As noted, most folding knives also include mechanisms that lock the blade in the open position, again, primarily as a safety feature. There are many different types of these locks.
Manual and automatic knives have many uses and can be used in many different settings, and that has led to a demand expressed by many knife users for knives that are operable in dual modes, both automatic and manual. There are benefits to be had in knives that have dual modes of operation and there are a few known dual mode knives. For instance, dual mode knives are described in U.S. Pat. Nos. 7,603,778 and 8,046,923. Nonetheless, there is a continuing need for improved mechanisms for enabling dual operational modes in a folding knife, manual and automatic.
The present invention comprises a folding knife having mechanisms for facilitating dual operational modes. In a first modality, the knife is opened and closed manually. In a second modality, the knife is fully automatic. The user is able to use the knife in either mode, manual or automatic. In the automatic mode a bolster is operable to move a lever in the interior of the knife between first and second positions; the bolster defines a trigger that causes the blade to move automatically from the closed to the open position. The lever in the interior of the knife has one end pivotally attached to one of the handle and its second end resident in a cavity in the bolster, which is slidably movable to move the lever to fire the knife in the automatic mode.
The knife utilizes two torsion springs to drive the blade automatically from closed to open, one spring on each side of the blade and each around the pivot shaft that connects the blade to the handle. The springs are retained in a slotted bushing and drive the blade open when the automatic opening actuator is operated. One end of each spring is fixed to the handle. The opposite ends of the springs interact with the blade—the springs operate on the blade when in auto mode but do not operated on the blade when in the manual mode. The knife further incorporates a dry fire safety mechanism that prevents firing of the automatic opening mechanisms when the blade has been opened manually, and thereby prevents damage to the automatic opening mechanisms.